Encoder, motor, and method for manufacturing encoder

Abstract

To enhance productivity of an encoder. An encoder (20) disclosed herein includes: a boss (25) that rotates about a rotation axis of a shaft included in a motor; a circular rotating plate (21) that is fixed to the boss (25) and rotates about the rotation axis; a bonding portion (27) that fixes the boss (25) and the rotating plate (21); and an optical module including a light source that irradiates the rotating plate (21) with light and a light receiving element that receives light emitted from the light source and reflected by the rotating plate (21). Bonding portion (27) includes a cured product of an adhesive having a photocuring property and an anaerobic curing property. A part of bonding portion (27) is exposed from between boss (25) and rotating plate (21) and is in contact with boss (25) and rotating plate (21).

1 . An encoder comprising:
 a boss that rotates about a rotation axis of a shaft included in a motor;   a rotating plate that has a circular shape, is fixed to the boss, and rotates around the rotation axis;   a bonding portion that fixes the boss and the rotating plate; and   an optical module including a light source that irradiates the rotating plate with light and a light receiving element that receives light emitted from the light source and reflected by the rotating plate,   wherein the bonding portion includes a cured product of an adhesive having a photocuring property and an anaerobic curing property, and   wherein a part of the bonding portion is exposed from between the boss and the rotating plate and is in contact with the boss and the rotating plate.   
     
     
         2 . The encoder according to  claim 1 , wherein the boss includes a first facing surface that faces the rotating plate and is in contact with the bonding portion in a direction along the rotation axis of the shaft. 
     
     
         3 . The encoder according to  claim 2 , wherein a ratio S 1 /S 2  of an area S 1  of the part of the bonding portion to an area S 2  of the first facing surface when viewed from a direction along the rotation axis is 0.2 or more. 
     
     
         4 . The encoder according to  claim 2 or 3 , wherein the boss has an edge provided on an inner peripheral side or an outer peripheral side of the rotating plate, the edge protruding toward the rotating plate from the first facing surface in a direction along the rotation axis. 
     
     
         5 . The encoder according to  claim 4 ,
 wherein the rotating plate includes a second facing surface that faces the first facing surface in the direction along the rotation axis and is in contact with the bonding portion, and a reflecting surface on an opposite of the second facing surface, and   wherein a projection end of the edge is closer to a base end of the edge than the reflecting surface in the direction along the rotation axis.   
     
     
         6 . The encoder according to any one of  claims 1 to 5 , wherein the boss has a recess on an inner peripheral side and/or an outer peripheral side of the rotating plate, the recess being recessed away from the rotating plate in the direction along the rotation axis. 
     
     
         7 . A motor comprising:
 the encoder according to any one of claims  1  to  6 ;   a shaft attached to the boss;   a rotor attached to the shaft; and   a stator facing the rotor.   
     
     
         8 . A method for manufacturing an encoder, the method comprising:
 a preparation step of preparing a boss and a rotating plate;   an application step of applying an adhesive having a photocuring property and an anaerobic curing property to at least one of the boss and the rotating plate;   a positioning step of positioning the boss and the rotating plate to expose a part of the adhesive from between the boss and the rotating plate and bring the part of the adhesive in contact with the boss and the rotating plate; and   a temporary fixing step of temporarily fixing the boss and the rotating plate by photocuring at least the part of the adhesive.   
     
     
         9 . The method according to  claim 8 , further comprising a main fixing step of forming a bonding portion that mainly fixes the boss and the rotating plate by anaerobically curing an uncured portion of a remainder of the adhesive.